The present invention relates to a receiver device such as, a paging receiver or the like utilizing, for instance, a multi-area roaming service in paging services, and a receiving channel setting method used therefor.
This application is based on Japanese Patent Application No.9-132384, filed May 22, 1997 and Japanese Patent Application No. 9-154870, filed Jun. 12, 1997, the contents of which are incorporated herein by reference.
Generally, paging receivers are becoming widely popular even among youths, and recently, in paging systems represented by the high-grade radio paging system (RCR STD-43 Standard), the service areas in the whole of a country are covered by 36 channel frequencies, whereby a so-called multi-area roaming service is achieved according to which it is possible for a user to receive a message addressed to the user wherever the user may be.
FIG. 26 shows the format of the transmitting data in this high-grade paging system, wherein data divided by cycle numbers "No. 0"-"No. 14" is transmitted in one hour, and further, in each of the cycles, 128 FRAMES numbered as "No. 0"-"No. 127" are transmitted.
The respective frames, which each correspond to 1.875 [sec], are each comprised of a first synchronizing portion S1, a frame information FI, a second synchronizing portion S2, a block information BI, an address field AF, a vector field VF, a message field MF and an idle block IB in this order.
In the frame information FI, there is contained a cycle number, a frame number, a roaming network bit RNB. The cycle number and the frame number indicate that the frame is included in which frame and cycle. The roaming network bit is an identification bit indicating whether or not the channel has a roaming service. If the roaming network bit is "1", it indicates that the channel has a roaming service.
If the user is in a service area where the paging service company provides a multi-area roaming service, a network identifier NID is set in the address field AF in every 8 frames. Stated another way, the NID is set in the frame number which is a modulo 8 of (M+N+C). Here, M is a modulo 8 of an integer part of a division of channel frequency by channel interval, N is a modulo 8 of the network address, and C is the cycle number. If the user changes the service area to a new one, the user receives the NID of the area in which he wants to receive a message, whereby the receiver is adjusted to the channel frequency to which this NID is set, and then, he or she transmits to the exchange for this service area, by the use of the nearest telephone set or the like, the service code of the multi-area roaming service, the password previously determined through the exchange in this service area, and the area No. of the area in which the service is to be received. Thus, the registration of the service area is finished.
In the transmitting data format of the multi-area roaming service, a local identifier LID is set separately from the NID; it is set in one of the second to fourth code words of the block information BI in every frame.
FIG. 27 shows the data format of the first code word of the block information BI which comprises check bits.times.(4 bits), a word number p (4 bits) of the priority address of the address field AF, a termination word a (2 bits) of the block information BI, a start word v (6 bits) of the vector field VF, a frame continuation flag d (2 bits), a variable receiving cycle value m (3 bits), and check bits (11 bits) including an even parity.
On the other hand, FIG. 28 shows the data format of the second to fourth code words of the block information BI, which comprises check bits.times.(4 bits), a format type f (3 bits), data s (14 bits), and check bits (11 bits) including an even parity.
If the value of the format type f is "111", SSID1 comprising a local channel identifier LID (9 bits) and a coverage zone (5 bits) are set in the data s as shown in FIG. 29. If the value of the format type f is "000", SSID2 consisting of a country identification code (10 bits) and a roaming traffic flag (4 bits) are set in the data s.
The SSID1 and SSID2 are both set as a pair in the block information BI, and, as for the LID thereof, the same one is set if a plurality of receiving channels are used in one service area.
However, if the change of the service area and the area registration are performed in a paging service in which the multi-area roaming service is provided by the use of such data formats as mentioned above, the user receiver terminal sweeps the respective channels until the NID is detected, in accordance with the scan list of the channel frequency to be received, which has been previously set as ID information, without regard to environmental circumstances such as "the radio waves of what channel frequencies are arriving around him" and "whether the data of the desired bit rate can be received". As a result, there is caused the inconvenience that a very long time such as, for example, more than one minute, is spent for the setting of the receiving channel, during which period the user always feels uneasy, wondering if he can receive the paging service in the particular service area.